This is an observational, prospective, longitudinal, follow-up study. Motor development was assessed by Alberta Infant Motor Scale (AIMS) and Peabody Developmental Motor Scales, Second Edition (PDMS II); motor function was assessed by Pediatric Evaluation of Disability Inventory (PEDI) and Gross Motor Function Measure (GMFM). Electrodiagnosis studies include nerve conduction study (NCS) and electromyography (EMG).